Thin film transistor-liquid crystal display and manufacturing method therefor

ABSTRACT

This invention relates to a TFT-LCD and a manufacturing method therefor which etches triple layer patterns in a single process step. As a result, the number of masking processes is reduced and a high quality device is produced with less defects. The method comprises the steps of: depositing a gate metal on a substrate; forming and a gate pad a gate electrode by etching the gate metal; forming an insulating layer on both the gate metal and the gate pad; depositing an amorphous silicon layer on the insulating layer; depositing an n+ amorphous silicon layer on the amorphous silicon layer; depositing a source/drain on the n+ amorphous silicon layer; etching the amorphous silicon, the n+ amorphous silicon layer and the source/drain to form a triple layer pattern; etching the n+ amorphous silicon layer and the source/drain to form a source/drain electrode; depositing a passivation layer; etching a passivation layer to expose both a portion of the source/drain electrode and a portion of the gate pad; depositing a pixel electrode layer on the passivation layer; and etching the pixel electrode layer to form a pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 10/113,491, filed Mar. 29, 2002, by Dong-Gyu Kim, entitled “THIN FILM TRANSISTOR-LIQUID CRYSTAL DISPLAY AND MANUFACTURING METHOD THEREFOR;” which is a continuation of U.S. patent application Ser. No. 08/600,132 filed Feb. 12, 1996, now U.S. Pat. No. 6,406,949, which issued Jun. 18, 2002, which claims priority of Korean Patent Application No. 95-2509 filed Feb. 11, 1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film transistor-liquid crystal display (hereinafter referred to as a TFT-LCD) and a manufacturing method therefor. More particularly, this invention relates to a TFT-LCD and a manufacturing method therefor which etches multi-layer patterns in a single process step.

2. Description of the Related Art

A conventional TFT-LCD is disclosed in Society for Information Display '94 DIGEST, page 263, the content of which is hereby expressly incorporated by reference herein in its entirety. That TFT-LCD will now be described with reference to FIGS. 1, 2A-2H, and 3A-3H.

In FIG. 1, a conventional TFT-LCD is depicted which comprises: a substrate 1, a gate electrode 2, an anodic oxidation layer 3, an insulating layer 4, an amorphous silicon layer 5, an n+ amorphous silicon layer 6, a source/drain electrode 9, a passivation layer 10, and a pixel electrode layer 13.

FIGS. 2A-2H show several cross-sectional views depicting different stages of a fabrication sequence for the conventional TFT-LCD shown in FIG. 1. FIGS. 3A-3H show cell views of layouts corresponding to the steps illustrated in FIGS. 2A-2H, respectively. Some layers are omitted from the cell layout views of FIGS. 3A-3H for purposes of simplification. Referring to those figures, a conventional method for fabricating a TFT-LCD generally comprises the steps of:

forming a gate pad 21, a gate electrode 2, and a gate line by depositing and etching a metal layer on a substrate 1;

forming a anodic oxidation layer 3 on both the gate electrode 2 and a portion of the gate pad 21;

depositing an insulating layer 4;

depositing an amorphous silicon layer 5 on the insulating layer 4;

depositing an n+ amorphous silicon layer 6 on the amorphous silicon layer 5;

etching both the amorphous silicon layer 5 and the n+ amorphous silicon layer 6 to form an active island 56;

partially etching the insulating layer 4 on the gate pad 21;

forming both a source/drain electrode 9 and a data line by depositing and etching a metal layer;

forming a passivation layer 10 having a contact hole 12 by depositing and etching an insulating material; and

forming a pixel electrode 13 by depositing and etching a transparent conductive material.

The above-described conventional TFT-LCD has many problems.

First, it reduces production yield. In addition, the etchants used during the etching process steps cause defects in the resulting TFT-LCD.

Moreover, it is more costly because many etching processes are employed in its fabrication.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a TFT LCD and a manufacturing method therefor which etches multi-layer patterns in a single process step. Accordingly, the present invention not only reduces the number of masking processes but also produces a high quality device with less defects.

In order to achieve this objective, a method is provided for manufacturing a TFT-LCD according to the present invention, which comprises the steps of:

depositing a gate metal on a substrate;

forming a gate electrode and a gate pad by etching the gate metal;

depositing an insulating layer;

depositing an amorphous silicon layer;

depositing an n+ amorphous silicon layer on the amorphous silicon layer. depositing a source/drain layer on the n+ amorphous silicon layer;

etching the source/drain layer, the n+ amorphous silicon layer, and the amorphous silicon layer to form a triple layer pattern in a single process step;

etching the source/drain layer and the n+ amorphous silicon layer to form a source/drain electrode pattern; depositing a passivation layer;

etching a passivation layer to expose both a portion of the source/drain electrode and a portion of the gate pad;

depositing a pixel electrode on the passivation layer; and

etching the pixel electrode;

A TFT-LCD according to the present invention includes: a gate electrode and a gate pad that are formed on a substrate; an insulating layer having a contact hole exposing the gate pad; an amorphous silicon layer which is formed on the insulating layer; a source/drain electrode which is formed on the amorphous silicon layer; a passivation layer, having contact holes which are formed on both the source/drain electrode and the gate pad; and a pixel electrode layer formed on the passivation layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more specifically with reference to the attached drawings, wherein: FIG. 1 shows a conventional TFT-LCD;

FIGS. 2A-2H show cross sectional views depicting a fabrication sequence for producing a conventional TFT-LCD.

FIGS. 3A-3H show cell layout views depicting the steps as illustrated in FIGS. 2A-2H respectively.

FIG. 4 shows a TFT-LCD according to a preferred embodiment of the present invention;

FIGS. 5A-5G are cross sectional views showing sequential steps of a method of producing the TFT-LCD of FIG. 4; and

FIGS. 6A-6G are cell layout views of the steps as illustrated in FIGS. 5A-5G.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will become apparent from a study of the following detailed description, when viewed in light of the accompanying drawings.

FIG. 4 shows a TFT-LCD according to a preferred embodiment of the present invention. A gate electrode 22 and a gate pad 21 are provided, each formed on a substrate 20. An anodic oxidation layer 23 is provided which is formed on both the gate electrode 22 and the gate pad 21. An insulating layer 24 is deposited on the anodic oxidation layer 23, and comprises a contact hole exposing the gate pad 21. An amorphous silicon layer 25 is formed on the insulating layer 24. A source/drain electrode 29 is formed on the amorphous silicon layer 25. A passivation layer 30 made of insulating material is formed on the source/drain electrode 29 and has a contact hole exposing the gate pad 21.

A manufacturing method for producing a TFT-LCD according to a preferred embodiment of the present invention is shown in FIGS. 5A-5H and 6A-6H. FIGS. 5A-5H show cross-sectional side views of the device during various fabrication stages, and

FIGS. 6A-6H show corresponding cell layout views. Some layers are omitted from the cell layout views of FIGS. 6A-6H for purposes of simplification.

As shown in FIGS. 5A and 6A, a gate metal is deposited on a substrate 20. Then, the gate electrode 22 and the gate pad 21 are formed by etching the gate metal.

As shown in FIG. 5B and FIG. 6B, an anode oxidation layer 23 is formed on both the gate electrode 22 and the gate pad 21.

As shown in FIG. 5C and FIG. 6C, an insulating layer 24 is then deposited on the anode oxidation layer 23. Then an amorphous silicon layer 25 is deposited on the insulating layer 24. Then an n+ amorphous silicon layer 26 is deposited on the amorphous silicon layer 25. Then a source/drain electrode metal 29 is deposited on the n+ amorphous silicon layer 25.

As shown in FIG. 5D and FIG. 6D, the source/drain 29, the n+ amorphous silicon layer 26 and the amorphous silicon 25 are etched to form a triple layer pattern.

As shown in FIG. 5E and FIG. 6E, the source/drain 29 and the n+ amorphous silicon layer 26 are etched to form a source/drain pattern, partially exposing amorphous silicon layer 25.

As shown in FIGS. 5F and 6F, a passivation layer 30 is deposited on the source/drain 29 and the gate pad 21. Then, the passivation layer 30 is etched, together with portions of anode oxidation layer 23 and insulating layer 24, to expose both a portion of the source/drain 29 and a portion of the gate pad 21.

At this time, when both the insulating layer 24 and the anodic oxidation layer 23 on the gate pad 21 are partially etched, portions of the insulating layer 24 and the anodic oxidation layer 23 which are on the gate electrode 22 are protected from the etchant because they are covered with the source/drain layer 29.

As shown in FIG. 5G and FIG. 6G, a pixel electrode 31 is deposited on the passivation layer 30. Then a pixel electrode pattern is etched.

As described above, this invention not only reduces steps of the masking process but also producing a high quality device with less defects.

It is understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be construed as encompassing all the features of patentable novelty that reside in the present invention, including all features that would be treated as equivalents thereof by those skilled in the art which this invention pertains. 

1. A thin film transistor-liquid crystal device (TFT-LCD), the thin film transistor comprising: a gate electrode and a gate pad formed on a substrate; a first insulating layer covering the gate electrode and having an opening exposing the gate pad; an amorphous silicon layer formed on the first insulating layer and having a channel portion; an n+ amorphous silicon layer formed on the amorphous silicon layer; a source electrode and a drain electrode formed on the n+ amorphous silicon layer; a passivation layer covering the source and drain electrodes and having a first contact hole exposing the gate pad and a second contact hole exposing the drain electrode, the passivation layer contacting with a side of the amorphous silicon layer, a side of the n+ amorphous silicon layer and a side of the drain electrode, and a pixel electrode formed on the passivation layer and electrically connected with the drain electrode through the second contact hole.
 2. The TFT-LCD of claim 1, wherein the passivation layer contacts the amorphous silicon layer at the channel portion.
 3. The TFT-LCD of claim 1, wherein the amorphous silicon layer, the n+ amorphous silicon layer and the source and the drain electrodes have substantially a same planar shape except for the channel portion.
 4. The TFT-LCD of claim 1, wherein the first contact hole of the passivation layer is larger than the opening of the first insulating layer.
 5. The TFT-LCD of claim 1, wherein the pixel electrode overlaps the n+ amorphous silicon layer in part.
 6. The TFT-LCD of claim 1, further comprising, a second insulating layer between the gate electrode and the first insulating layer. 